Merge pull request #290 from gyorilab/parse_curly_braces

Implement safe parsing of curly braces

mira/metamodel/utils.py

@@ -8,15 +8,22 @@
 
 def get_parseable_expression(s: str) -> str:
  """Return an expression that can be parsed using sympy."""
+ # Handle lambda which cannot be parsed by sympy
  s = s.replace('lambda', 'XXlambdaXX')
+ # Handle dots which also cannot be parsed
  s = re.sub(r'\.(?=\D)', 'XX_XX', s)
+ # Handle curly braces which are not allowed in sympy
+ s = s.replace('{', 'XXCBO').replace('}', 'XXCBC')
  s = unicodedata.normalize('NFKC', s)
  return s
 
 
 def revert_parseable_expression(s: str) -> str:
  """Return an expression to its original form."""
- return s.replace('XXlambdaXX', 'lambda').replace("XX_XX", ".")
+ s = s.replace('XXCBO', '{').replace('XXCBC', '}')
+ s = s.replace('XX_XX', '.')
+ s = s.replace('XXlambdaXX', 'lambda')
+ return s
 
 
 def safe_parse_expr(s: str, local_dict=None) -> sympy.Expr:

tests/test_metamodel.py

@@ -240,7 +240,13 @@ def test_from_askenet_petri_mathml():
  assert mathml_str == org_str
 
 
-def test_safe_parse():
+def test_safe_parse_nfkc():
  eps = 'ϵ'
  eps_sym = sympy.Symbol(eps)
  assert safe_parse_expr(eps, local_dict={eps: eps_sym}) == eps_sym
+
+
+def test_safe_parse_curly_braces():
+ var = 'x_{a}'
+ var_sym = sympy.Symbol('x_{a}')
+ assert safe_parse_expr(var, local_dict={var: var_sym}) == var_sym